Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

biochem 2 > Untitled Deck > Flashcards

Untitled Deck Flashcards

(92 cards)

Start Studying
1
Q

What are enzymes defined as?

A

Biocatalysts synthesized by living cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the nature of enzymes?

A

Enzymes are protein in nature, colloidal, thermolabile in character, and specific in action.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can the function of enzymes be compared to a teacher?

A

A teacher enhances the understanding ability of students like a catalyst enhances reaction rates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are substrates in relation to enzymes?

A

The substances on which enzymes act to convert them into products.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do enzymes do to reaction rates?

A

They accelerate reactions at least a million times by reducing the energy of activation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are monomeric enzymes?

A

Enzymes with only one polypeptide chain in their structure, e.g., ribonuclease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are oligomeric enzymes?

A

Enzymes with more than one polypeptide chain, e.g., lactate dehydrogenase and hexokinase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a subunit in the context of oligomeric enzymes?

A

Each single polypeptide chain of an oligomeric enzyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a multienzyme complex?

A

When many different enzyme catalyzing sites are located at different areas of the same macromolecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to a multienzyme complex when it is broken down?

A

It becomes inactive.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are enzymes generally named?

A

By adding the suffix ‘ase’ to the name of the substrate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are proenzymes?

A

Inactive forms of enzymes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is autocatalysis?

A

The process where the active form of the enzyme acts on the zymogen to catalyze its conversion into the active form.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What classification system does the International Union of Biochemistry use for enzymes?

A

A nomenclature system based on chemical reaction type and reaction mechanism.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many classes are enzymes grouped into according to the IUB system?

A

Seven classes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name the seven classes of enzymes.

A
  • Oxidoreductases
  • Transferases
  • Hydrolases
  • Lyases
  • Isomerases
  • Ligases
  • Translocases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do oxidoreductases do?

A

They are involved in oxidation-reduction reactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Provide an example of an oxidoreductase.

A

Alcohol dehydrogenase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are transferases responsible for?

A

Catalyzing the transfer of a particular group from one substrate to another.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Provide an example of a transferase.

A

Aspartate transaminase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do hydrolases do?

A

Bring about hydrolysis of various compounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Provide an example of a hydrolase.

A

Lipase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are lyases involved in?

A

The removal of a small molecule from a large substrate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Provide an example of a lyase.

A

Aldolase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What do isomerases catalyze?
Isomerization reactions.
26
Provide an example of an isomerase.
Phospho triose isomerase.
27
What do ligases do?
Join together two substrates.
28
Provide an example of a ligase.
Glutamine synthetase.
29
What are translocases responsible for?
Assisting in the movement of ions or molecules across membranes.
30
Provide an example of a translocase.
ADP/ATP translocase.
31
What are synthetases?
ATP-dependent enzymes catalyzing biosynthetic reactions.
32
What are synthases?
Enzymes catalyzing biosynthetic reactions without requiring ATP directly.
33
What is a coenzyme?
A non-protein, organic, thermostable, low molecular weight substance associated with enzyme function.
34
What is a holoenzyme?
The functional enzyme made up of an apoenzyme and a coenzyme.
35
What are some examples of coenzymes derived from B complex vitamins?
* Thiamine pyrophosphate (TPP) * Flavin mononucleotide (FMN) * Nicotinamide adenine dinucleotide (NAD)
36
What are non-vitamin coenzymes?
Organic substances that function as coenzymes but have no relation to vitamins.
37
What is the difference between metal activated enzymes and metalloenzymes?
* Metal activated enzymes: The metal is not tightly held and can be exchanged. * Metalloenzymes: The metal is held tightly and is not readily exchanged.
38
What is a cofactor?
A collective term that includes coenzymes and metal ions.
39
What is enzyme specificity?
Enzymes are highly specific in their action, leading to thousands of enzymes in biological systems.
40
What are the types of enzyme specificity?
* Optical specificity * Reaction specificity * Substrate specificity
41
What is optical specificity?
Only one optical isomer of a substrate acts as a substrate for an enzyme.
42
What is reaction specificity?
Each reaction of a substrate is catalyzed by its own specific enzyme.
43
What is absolute substrate specificity?
Certain enzymes act only on one substrate.
44
What is broad substrate specificity?
Some enzymes act on closely related substrates.
45
What is the active site of an enzyme?
The specific site on the enzyme molecule where a substrate can bind.
46
What is formed when an enzyme combines with a substrate?
An enzyme-substrate complex (ES).
47
What is the relationship between enzyme (E), substrate (S), and product (P) in enzyme action?
E + S → ES → E + P
48
What is the site called where a substrate binds to an enzyme?
Active site
49
What is the molecular size comparison between substrate and enzyme?
The substrate molecule is extremely small compared to the enzyme molecule.
50
What characterizes the active site of an enzyme?
It is made up of amino acids far apart in the primary structure and forms due to folding in secondary and tertiary structures.
51
Which enzyme has an active site formed by amino acids numbered 35, 52, 62, 63, and 101?
Lysozyme
52
How is the active site described in terms of its structure?
Active sites are clefts, crevices, or pockets and are flexible.
53
What type of bonds does the substrate use to bind to the active site?
Weak non-covalent bonds
54
What are the most commonly found amino acids at the active site?
* Serine * Aspartate * Histidine * Cysteine * Lysine * Arginine * Glutamate * Tyrosine
55
What model describes the enzyme action where the active site is a pre-shaped template?
Lock and key model
56
Who proposed the lock and key model of enzyme action?
Emil Fischer
57
What is the key feature of the induced fit model of enzyme action?
The active site is flexible and changes shape to fit the substrate.
58
Who proposed the induced fit model?
Daniel Koshland
59
What happens to the substrate when it binds to the active site according to the substrate strain theory?
The enzyme induces strain on the substrate.
60
What does Km, the Michaelis-Menten constant, represent?
The substrate concentration required to produce half maximum velocity in an enzyme-catalyzed reaction.
61
What happens to the Km value in competitive inhibition?
Km value increases while Vmax remains unchanged.
62
What is the effect of non-competitive inhibition on Km and Vmax?
Km is unchanged and Vmax decreases.
63
What is the effect of uncompetitive inhibition on Km and Vmax?
Both Km and Vmax decrease.
64
List the factors affecting enzyme action.
* Temperature * pH * Enzyme concentration * Product concentration * Substrate concentration * Coenzymes * Metal ion activators * Inhibitors * Light and radiation
65
What is the optimum temperature range for most enzymes?
35 to 40 degrees Celsius
66
What happens to enzyme activity at temperatures above 70 degrees Celsius?
Majority of enzymes become inactive.
67
What is the optimum pH range for most enzymes?
6 to 8
68
What are examples of enzymes with specific optimum pH values?
* Pepsin: pH 1 to 2 * Acid phosphatase: pH 4 to 5 * Alkaline phosphatase: pH 10 to 11
69
How does enzyme concentration affect reaction velocity?
Velocity is directly proportional to enzyme concentration.
70
What effect does product concentration have on enzyme activity?
Excess product may lower reaction velocity by occupying the active site.
71
What role do coenzymes play in enzymatic reactions?
They are required for enzyme action and are non-protein, organic substances.
72
Provide examples of coenzymes.
* TPP for transketolase * NAD for lactate dehydrogenase
73
What are metal ion activators and give examples?
* Required for enzyme activity * Examples: Molybdenum for xanthine oxidase, Iron for cytochrome oxidase, Zinc for alcohol dehydrogenase
74
What is an enzyme inhibitor?
A substance that binds to the enzyme and decreases its activity.
75
List examples of enzyme inhibitors.
* Oxamate inhibits lactate dehydrogenase * Malonate inhibits succinate dehydrogenase * Sodium fluoride inhibits enolase * Cyanide inhibits cytochrome oxidase
76
What is allosteric regulation?
Regulation of enzyme activity through binding at allosteric sites.
77
What are the two types of allosteric sites?
* Activator sites * Inhibitor sites
78
What is the significance of allosteric enzymes?
They regulate metabolic pathways and are often key or rate-limiting enzymes.
79
What is covalent modulation in enzyme regulation?
Regulation through the addition or removal of phosphate groups.
80
What are proenzymes or zymogens?
Non-functional forms of enzymes that require proteolytic trimming to become active.
81
Provide an example of a proenzyme.
Pepsinogen to pepsin
82
What is the process of converting proenzymes or zymogens into active enzymes called?
Proteolytic trimming ## Footnote This process involves proteolytic cleavage to activate the enzymes.
83
What is an example of a proenzyme that is converted to its active form?
Pepsinogen to pepsin ## Footnote Other examples include trypsinogen to trypsin and plasminogen to plasmin.
84
What are the two forms of protein modulation in enzyme activity?
Covalent modulation and proteolytic trimming ## Footnote Covalent modulation involves phosphorylation and dephosphorylation of enzymes.
85
What is the role of protein kinase in enzyme activity?
Adds phosphate groups to enzymes ## Footnote This process can activate or deactivate enzymes depending on the context.
86
What is the role of protein phosphatase in enzyme activity?
Removes phosphate groups from enzymes ## Footnote This can also affect the activity of the enzymes.
87
What is the relationship between anabolism and catabolism in metabolic pathways?
They usually do not occur simultaneously ## Footnote When one is active, the other is typically suppressed.
88
Where does fatty acid synthesis occur?
In the cytosol ## Footnote Fatty acid oxidation, on the other hand, occurs in the mitochondria.
89
Fill in the blank: Certain enzymes are synthesized as _______ or zymogens, which are non-functional.
proenzymes
90
True or False: Major biomolecules in the body are synthesized and degraded simultaneously.
False ## Footnote These processes typically occur in separate cellular organelles.
91
What is the general trend regarding the processes of synthesis and degradation in metabolism?
When one process is up, the other one is down.
92
Name one example of proteolytic trimming of an enzyme.
Trypsinogen to trypsin ## Footnote Other examples include pro-elastase to elastase.

biochem 2 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions